Videocassettes are well known for storing and using magnetic recording tape. A length of magnetic tape is wound onto a supply reel and the free end of the tape is wound onto a takeup reel. Both reels are contained in a housing which can be inserted into a suitable playing or recording apparatus (VCR) such as those of the VHS format.
An important feature of VHS videocassettes is the ability to brake and lock the tape reels against unwanted rotation to prevent unwinding of the tape when the videocassette is not in use. Conventional reel locking devices for VHS videocassettes typically are mounted along a rear wall between the two reels. These devices include locks, which are pivotally mounted levers, or pawls, which engage notches located on the outer periphery of the bottom flanges of the supply and take-up reels. These locking pawls are typically held in engagement with the flanges by one or more springs.
A release device, which is typically an L-shaped release lever, is pivotable around a horizontal axis. The release lever is rotated upon insertion of the videocassette into the VCR by a release pin which enters an aperture in the bottom of the videocassette housing. Rotation of the release lever urges the pawls away from the reel flanges, freeing the reels and allowing them to be driven by the VCR. Typical reel locking devices of this type are disclosed in U.S. Pat. Nos. 4,106,724; 4,232,840; and 4,974,108.
These reel locking devices operate satisfactorily and reliably. The pivoting release levers require a low level of force to operate and having a low level of debris generation due to wear. However, these reel locking devices have several parts. This places a significant economic burden on manufacturers who operate in the price-competitive videocassette market. As a result, several simplifications of the lever-operated pawl and spring devices have been devised.
U.S. Pat. Nos. 4,512,534 and 4,623,105 disclose reel locking devices in which the springs for holding the pawls in engagement with the reels are integrally molded resilient plastic portions of the pawls. A further step in part integration is disclosed in UK Patent Application No. GB 2 099 400, in which both of the pawls and a resilient engagement member connecting them are molded as a single part. This reduces the number of parts to just two--the release lever and the pawl-spring combination.
U.S. Pat. No. 5,216,564 discloses a one piece reel locking device for video cassettes. However, this device requires the spring portion to push against the rear wall of the cassette, and to unlock the reel this device requires that the locking portions extend out of the plane of the reel lower flanges and into the plane of the tape path.